Intensity controllable hand-held surgical light

ABSTRACT

A hand-held surgical light assembly is provided with a light source, and a handpiece which is adapted to be grasped and manipulated by a user. The handpiece has a light guide with a proximal end optically connected to the light source, and a distal end which projects outwardly from said handpiece so as to direct light guided thereby onto a field of view determined by manipulation of the handpiece by the user. The handpiece includes a switch assembly which is operatively coupled to the light source to allow user selection between at least two different light intensities (e.g., essentially on/off) discharged by said light guide onto the field of view. In preferred forms, the switch assembly includes an electrically conductive inner base member and an electrically conductive outer tubular elastomeric member concentrically positioned in surrounding, but spaced relationship, with the inner base member. When contact between the inner base member and the outer elastomeric member is made, switch circuitry changes the visible light intensity of the visible light generated by the light source, e.g., by either directly modulating the current to the lamp itself, or by providing an electrically operable shutter assembly which masks the light generated by the light source. The former embodiment is especially well suited for surgical lights which are self-contained (i.e., have the light sources contained in the handpiece), while the latter is especially well suited for surgical lights which have remotely positioned light sources.

This is a divisional of application Ser. No. 09/286,659, filed Apr. 6,1999, now pending, the entire content of which is hereby incorporated byreference in this application.

FIELD OF THE INVENTION

The present invention relates generally to visible light-producingimplements used in surgical arenas, especially during ophthalmicsurgical procedures. In preferred forms, the present invention isembodied in a hand-held light that permits the surgeon (or otherattending surgical personnel) to locally controllably adjust the emittedlight intensity.

BACKGROUND AND SUMMARY OF THE INVENTION

Photon energy delivered to the retina from intraocular fiberopticinstruments during ophthalmic surgical procedures can damage the retina.Retinal damage occasioned by such photon energy is known colloquially inthe ophthalmic surgical art as “fight toxicity”. As a result, concernshave arisen over the amount of photon energy being delivered to theretina during a normal surgical procedure. For example, wavelengths from400 nm to 700 nm are considered to be the safest for purposes ofophthalmic surgery.

However, even at these wavelengths, retinal damage can occur if retinalexposure to the photon energy is prolonged. In this regard, exposure ofthe retina to light emanating from intraocular fiberoptics duringretinal surgery has, in some cases, resulted in pathologic retinallesions, some of which have been associated with vision loss. Fiberopticillumination of the retina, however, remains an essential component ofvitreoretinal surgery in order for the surgeon to visualize the tissuesundergoing the surgical procedure.

Although the use of visible light within the eye during ophthalmicsurgery cannot be eliminated, the desire has been to reduce the amountof photon energy being delivered to the retina during a procedure. Forexample, light sources that have little of the most harmfulwavelengths—i.e., light sources which emit little or no photon energy atwavelengths other than between 400-700 nm—have been employed. However,as noted previously, retinal damage can ensue if exposure is prolongedeven at these relatively “safe” wavelengths. Furthermore, filters havealso been placed in the light path of the light source so as to blockthe less safe wavelengths. Also, attempts have been made to diffuse thelight over larger areas.

Conventional fiberoptic illuminators used to transmit photon energyduring ophthalmic surgery are typically formed of polymethylmethacrylate(PMMA) having a nominal numeral aperture (NA) of about 0.66. Most of theenergy from these conventional PMMA fiberoptic illuminators is within a60° cone of light. Some special use fiberoptic lights use glass fibersthat have similar optical properties. These conventional illuminatorsreceive their light energy from a standard light source with matchingoptics allowing for good collection of the energy into the fiber. Thefiberoptics are usually of an extended length (e.g., typically about six(6) feet in length) to allow the light emitting end to be used withinthe surgical field while the light source is maintained in a remotelocation. The fiberoptics are thus typically draped from the source tothe operating field. Since several fiberoptic lights can be in usesimultaneously during an operation, the fiberoptics tend to form atangle of cables running onto the operating field, thereby providingpractical complications.

Furthermore, during surgery, there exist the competing demands ofproviding the surgeon with adequate light to illuminate the surgicalfield, while at the same time permit relatively instantaneous adjustmentof the illumination when desired to thereby reduce the photon energydelivered during periods when full illumination is not needed for theprocedure. The surgeon can request that an assistant adjust theintensity of the light at the remotely positioned light source duringportions of the surgery when this is feasible or can direct the lightaway from the most critical portion of the retina (the macula) duringpauses in surgery. However, the former technique is problematic sincesurgical assistants are usually tasked with other responsibilities andthus may not be available to instantaneously adjust the light intensityat the surgeon's request. And, the latter technique may not always beavailable to the surgeon since the surgeon's hands may be occupiedphysically with another aspect of the surgical procedure which preventsredirection of the light.

Thus, as can be appreciated from the discussion above, improvements tosurgical lights have been needed. It is towards providing suchimprovements that the present invention is directed.

Broadly, the present invention is embodied in hand-held surgical lightassemblies having a light source, and a handpiece which is adapted to begrasped and manipulated by a user. The handpiece has a light guide witha proximal end optically connected to the light source, and a distal endwhich projects outwardly from said handpiece so as to direct lightguided thereby onto a field of view determined by manipulation of thehandpiece by the user. The handpiece includes a switch assembly which isoperatively coupled to the light source to allow user selection betweenat least two different light intensities (e.g., essentially on/off)discharged by said light guide onto the field of view.

In preferred forms, the switch assembly includes an electricallyconductive inner core and an electrically conductive outer tubularelastomeric member concentrically positioned in surrounding, but spacedrelationship, with the inner base. When contact between the inner baseand the outer elastomeric member is made, switch circuitry changes thevisible light intensity of the visible light generated by the lightsource, e.g., by either directly modulating the current to the lampitself, or by providing an electrically operable shutter assembly whichmasks the light generated by the light source. The former embodiment isespecially well suited for surgical lights which are self-contained(i.e., have the light sources contained in the handpiece), while thelatter is especially well suited for surgical lights which have remotelypositioned light sources.

These, and other, aspects and advantages will become more clear aftercareful consideration is given to the following detailed description ofthe preferred exemplary embodiments thereof.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Reference will hereinafter be made to the following drawings in whichlike reference numerals throughout the various FIGURES denote likestructural elements, and wherein,

FIG. 1 is a perspective view of a particularly preferred embodiment of aself-contained hand-held surgical light in accordance with the presentinvention;

FIG. 2 is a longitudinal cross-sectional view, partly schematic, of thehand-held surgical light depicted in FIG. 1;

FIG. 3 is a perspective view of another embodiment of a handheldsurgical light assembly in accordance with the present invention whichis especially well suited for use in combination with a remotelypositioned light source;

FIG. 4 is an enlarged longitudinal cross-sectional elevation view of thehandpiece of the embodiment depicted in FIG. 3;

FIG. 5 is a schematic depiction of a control circuit that may beemployed in connection with the switches associated with hand-heldsurgical light embodiments in accordance with the present invention;

FIGS. 6A and 6B respectively depict different operational states of ashutter assembly that may be employed in operative association with theremotely positioned light source used in surgical light assemblydepicted in FIG. 3;

FIGS. 7A and 7B respectively depict different operational states ofanother shutter assembly that may be employed in operative associationwith the remotely positioned light source used in surgical lightassembly depicted in FIG. 3;

FIGS. 8A and 8B are end elevational views of the shutter states depictedin FIGS. 7A and 7B, respectively, as taken along lines 8A—8A and 8B—8Btherein;

FIG. 9 is a rear perspective view of an embodiment of a rotary shutterassembly that may be employed in the surgical light assembly depicted inFIG. 3; and

FIG. 10 is a rear cross-sectional elevational schematic view of anembodiment of a rectilinearly moveable shutter assembly that may beemployed in the surgical light assembly depicted in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

One preferred embodiment of a hand-held surgical light 10 in accordancewith the present invention is depicted in accompanying FIGS. 1 and 2.The surgical light 10 shown in FIGS. 1 and 2 generally includes aproximal handle section 12 which is sized and configured to be heldcomfortably in a surgeon's hand, a distal end section 14, and a lightguide section 16 protruding distally from the end section 14.

The embodiment of the surgical light 10 shown in accompanying FIGS. 1and 2 is self-contained. That is, the surgical light 10 includes alloperational components such as power source 20 (e.g., preferably in theform of a conventional rechargeable battery), a light source 22 (e.g., aconventional incandescent microbulb), and the electronic switchcircuitry 24 are contained within the handle section 12, while amechanical membrane switch 26 is positioned operatively in the distalend section 14.

The light source 22 includes an ellipsoid mirror (not shown) whichfocuses the light onto the distally positioned conically shaped mirror24-1. The light then passes through a wave-length filter 24-2 wherepotentially harmful wavelengths are filtered therefrom (e.g., so thatonly photon energy having a wavelength between 400-700 nm passes throughthe filter 24-2). The filtered light is then directed into the proximalend of the light guide section 16 which is held securely within thedistal tip section 14 of the surgical light 10.

The filtered light then propagates along the light guide section 16 andis discharged from its distal tip onto the surgical field as directedmanually by the surgeon holding the light 10. Most preferably, the lightguide section includes a 19 gauge stainless steel (type 304) tubing inwhich a light conducting fiber is positionally fixed (e.g., by suitablebonding adhesive). The light conducting fiber is most preferably 0.75 mmdiameter and has a numerical aperture of about 0.6.

An electrical switch on the handle assembly will, when manuallyactivated, cause the intensity of the light emitted by the light source22 to change. The preferred switch according to this invention is amechanical membrane switch 26 which is comprised generally of an outerelectrically conductive tubular elastomeric membrane sleeve 26-1 and aninner electrically conductive generally cylindrical metal member 26-2.The membrane sleeve 26-1 is most advantageously is about 0.040 inchthick and has a hardness of about 55 Durometer and a resistance value ofabout 10 Kohms per square. One preferred electrically conductiveelastomeric sleeve that may be employed is Product No. F00120880000commercially available from Patter Products Inc. of Beaverton, Mich. Theelectrically conductive base member 26-2 is most preferably aluminum,for example, 6061 aluminum alloy.

As shown, the outer membrane sleeve 26-1 is separated from the innerconductive base member 26-2 by an annular space. In use, therefore, thesurgeon will depress the membrane sleeve 26-1 until it contactsphysically the base member 26-2 thereby electrically closing the switch26. The switch circuitry 24 (to be explained in greater detail belowwith regard to FIG. 5) is electrically connected to the switch viainternal wiring 28 and will therefore sense this switch closure.Generally, the switch circuitry will change the intensity of the lightemitted by the light source 22 in a step-wise manner in response toswitch closure. In this way, the surgeon can manually and selectivelycontrol the intensity of the light emitted from the distal end of thelight guide section 16.

Accompanying FIGS. 3-4 show another embodiment of a hand-held surgicallight 50 in accordance with the present invention. One principaldifference between the surgical light 50 depicted in FIGS. 3-4, and thesurgical light 10 depicted in FIGS. 1-2 is that the former is notself-contained. Instead, the surgical light 50 includes a remotelylocated light source 52 which is optically coupled through a shutterassembly 53 to a light probe handpiece 54 via conventional primaryoptical light guide 56.

The handpiece 54 includes a proximal cylindrical handle section 54-1sized and configured to allow a surgeon to manually manipulate it duringsurgical operations and a tapered distal end section 54-2. A light guidesection 58 similar to the light guide section 16 discussed previouslyprotrudes outwardly from the distal end section 54-2 of the handpiece54. The light guide section 58 is optically coupled to the light guide56 by means of a proximal, and unitary, section 58-1. The handpiece maybe coupled/uncoupled from the primary light guide 56 by an opticalcoupler 57.

According to the present invention, the handpiece 54 carries anelectrical switch which, according to the present invention, is mostpreferably a membrane switch assembly 70. As shown in FIGS. 3 and 4, themembrane switch assembly 70 is sized so as to be sleeved over the handlesection 54-1 and be in friction-fit engagement therewith. As is perhapsbetter seen in FIG. 4, the membrane switch 70 includes an outerconductive tubular elastomeric membrane sleeve 70-1 which concentricallysurrounds an inner cylindrical electrically conductive metal base member70-2. In its normal (non-active) condition, therefore, an annular spaceis defined between the membrane sleeve 70-1 and the base member 70-2.The membrane sleeve 70-1 and base member 70-2 are electrically isolatedfrom one another while in a normal condition by proximal and distalmounting rings 70-3 and 70-4, respectively. which are separated from oneanother along the axial direction of the handpiece 50. Most preferably,the electrically conductive elastomeric membrane sleeve 70-1 has thesame dimensions and properties as that described above with reference tomembrane sleeve 26-1 associated operatively with the surgical light 10.The membrane switch 70 is electrically connected to the switch circuitry100 via electrical wiring 70-5 traced along the optical light guide 56.Particularly, the switch circuitry 100 may be electrically coupled to asolenoid coil 102 (not shown in FIG. 3, but see FIG. 5) associatedoperatively with the shutter assembly 53.

Accompanying FIG. 5 depicts an exemplary switching circuit that may beemployed as the switch circuit 100 depicted in FIG. 3 or the switchcircuit 24 depicted in FIG. 2. Thus, the switch circuit 100 or 24 mayoperate alternatively a solenoid coil 102 (i.e., if employed in thehand-held surgical light 50) or a light assembly 22 (i.e., if employedin the hand-held surgical light 10), respectively. In this regard, asdiscussed previously, the mechanical membrane switch 26 (associated withthe surgical light 10) or 70 (associated with the surgical light 50) maybe activated by the surgeon to effect a change in light intensity in astep-wise manner (most preferably to toggle between on/off states). Themembrane switch 26 or 70 is electrically coupled to a flip-flopsemiconductor device 108 that controls whether current flows through theswitching solenoid coil 102 or light 22 by activating a transistor 110.

The membrane switch applies a reference voltage 112 to the clock inputof the flip-flop 108. When the clock signal is high, i.e., referencevoltage supplied by the membrane switch, the flip-flop is enabled.Enabling the flip-flop does not by itself cause the outputs 114, 116 tochange. The state of the outputs (Q, Q-bar) depends on the data input118 at the moment the flip-flop 108 is enabled. If the data input ishigh, then the output (Q) 114 will be switched high when the flip-flopis enabled by the membrane switch. As the output (Q) goes high, thentransistor 110 is turned on and current flows through the solenoid coil102 or light 22.

When the data input 118 is high at the moment the flip-flop 108 isenabled, the inverted output (Q-bar) 116 is switched low. The low stateof the Q-bar output will cause the data input 118 to fall to a low statedue to the operation of the resistor 122 and capacitor circuit 120 (R/C)connected between the Q-bar output and data input. As long as the datainput remains high and capacitor 120 has not discharged, subsequenttransitions of the enable signal such as those caused by bounce oruncertain pressure on the membrane switch will cause the Q output 114 toremain high, and transistor 110 will continue to conduct current throughthe solenoid coil 102 or light 22. After a period of time sufficient forcapacitor 110 to discharge through resistor 122 to the Q-bar output 116and allow the data input 118 to go low, a subsequent closure of themembrane switch will switch the Q output 114 low (and the Q-bar outputhigh). This will turn off transistor 110, which will therefore turn offsolenoid coil 102 or light 22. The action of resistor 122 and capacitor120 will delay the change of data input 118 to the level of Q-bar output116 as in the previous case, thereby again providing immunity toinadvertent enable signals caused by bounce or uncertain pressure on themembrane switch. This allows the surgeon to turn the light on or off bya momentary activation of the switch, and not have to maintaincontinuous pressure on the switch. Combining a multiplicity of circuitssimilar to this, in ways which are completely understood by thoseskilled in this art, allows for multiple levels of illumination to beselected by the surgeon.

The solenoid coil 102 can be associated operatively with a variety ofmechanical shutter systems 53, some embodiments of which will bedescribed below, in combination with the mechanical membrane switch 70.Thus, for example, the shutter assembly 53 may include a shuttle member135 which is fixed to, and moves axially within the solenoid coil 102.On energization (e.g., by closing the membrane switch 70 as discussedabove), as shown in FIG. 6A, the solenoid may drive the proximal section56-1 of the light guide 56 toward the rear face 140-1 of the opticalcoupling 140 which couples the light guide 56 to the light source 52. Inthis condition, the full intensity of the light produced by the lightsource 52 is allowed to enter and be transferred along the light guide56. When deenergized (e.g., by closing the membrane switch 70 asubsequent time), the shuttle 135 may be driven in an opposite axialdirection as shown in FIG. 6B. In response, therefore, the proximal endsection 56-1 of the light guide 56 is recessed within the coupling 140(i.e., is withdrawn from the face 140-1) thereby diminishing theintensity of the light from light source 52 which is allowed to bepropagated along the light guide 56.

Another possible shutter assembly 53 is depicted in accompanying FIGS.7A-7B and 8A-8B. In this embodiment, the shutter assembly 53 includes ashuttle member 135 which is coaxially moveable between a retractedposition (as shown in FIGS. 7A and 8A) and an advanced position (asshown in FIGS. 7B and 8B) within the solenoid coil 102 so as to allowmaximum and minimum light intensity to be received by the proximal endsection 56-1 of the light guide 56. The solenoid coil 102 is fixed to,and axially spaced from the optical coupling 140 by means of a bridgemember 142. A flexible shutter band 150 is attached physically at oneend 150-1 to the shuttle member 135 and has an opposite end 150-2 whichis capable of covering the entranceway 140-2 to the proximal light guidesection 56-1 when the light guide is in its extended position (i.e., asshown in FIGS. 7B and 8B). In this regard, the shutter band 150 isformed of a shape-retaining material and is most preferably bent orcurved at the end 150-2 so that, when it protrudes rearwardly from theface 140-1 of the coupling 140, it will bend over and cover theentranceway to the light guide section 56-1. Thus, operating themembrane switch 70 will responsively cause the terminal end 150-2 of theshutter band 150 to respectively be in either a covered and uncoveredrelationship with respect to the light guide section 56-1 therebyminimizing and maximizing the light it receives from the light source52.

FIG. 9 depicts another shutter assembly 53 that may be employed in thepractice of this invention. In this regard, instead of an axiallyoperable shutter mechanism, the solenoid coil 102 is operable in arotary direction. The solenoid coil 102 is connected to a proximal endof a drive shaft 160 which extends the entire length of the opticalcoupling member 104. A paddle-type shutter member 162 is fixed to thedistal end of the drive shaft 160. As shown in FIG. 9, operation of themembrane switch 70 causes the solenoid to activate which responsivelyrotates the drive shaft 160 and thereby swings the paddle-type shuttermember 162 into and out of covering relationship with the entranceway104-2 to the light guide 56 formed in the face 104-1 of the opticalcoupling 104. The intensity of the light emitted by the light guidesection 58 is thereby minimized and maximized, respectively.

Another paddle-type shutter member 170 is depicted in the shutterassembly 53 shown in FIG. 10. In this regard, the shutter member 170 isconnected operatively to a solenoid coil 102 which redially reciprocallymoves the shutter member 170 into and out of covering relationships withthe entranceway 140-2 of the light guide 56 formed in the face 140-1 ofthe optical coupling member 140. Again, therefore, according to theshutter embodiment depicted in FIG. 10, activation of the switch 70 willresponsively cause the shutter member 170 to cover and uncover the lightguide entranceway 140-2 thereby minimising and maximizing the intensityof light discharged from the light guide section 58.

Other equivalent forms and/or embodiments of the present invention, forexample, other forms and/or embodiments of the switch assemblies,shutter assembly, and the like, may be envisioned by those skilled inthis art. Therefore, while the invention has been described inconnection with what is presently considered to be the most practicaland preferred embodiment, it is to be understood that the invention isnot to be limited to the disclosed embodiment, but on the contrary, isintended to cover various modifications and equivalent arrangementsincluded within the spirit and scope of the appended claims.

What is claimed is:
 1. A hand-held surgical light assembly comprising: alight source; and a handpiece adapted to be grasped and manipulated by auser; wherein said handpiece has a light guide with a proximal endoptically connected to the light source, and a distal end which projectsoutwardly from said handpiece and directs light guided thereby onto afield of view determined by manipulation of the handpiece by the user;and wherein said handpiece includes a membrane switch assembly which isoperatively coupled to the light source to allow user selection betweenat least two different light intensities discharged by said light guideonto the field of view; and wherein said membrane switch assemblyincludes an inner electrically conductive base member, and a tubularelectrically conductive elastomeric member concentrically surroundingsaid base member in spaced relationship thereto.
 2. The hand-held lightassembly of claim 1, wherein said light source is contained within saidhandpiece.
 3. The hand-held light assembly of claim 2, wherein saidhandpiece includes a source of electrical power electrically connectedto said switch assembly and said light source.
 4. The hand-held lightassembly of claim 1, wherein said light source is remotely positionedrelative to said handpiece, and wherein said light source includes anelectrically-operable shutter assembly connected operatively to saidswitch assembly to effect said at least two different light intensities.5. The hand-held light assembly of claim 4, wherein said base member iscylindrical and is sleeved over said hand-piece.
 6. The hand-held lightassembly of claim 5, wherein said switch assembly includes proximal anddistal electrically non-conductive mounting rings which are fixed to andconcentrically separate said tubular electrically conductive elastomericmember and said electrically conductive base member.
 7. The hand-heldlight assembly of claim 4, 5 or 6, wherein said shutter assemblyincludes a solenoid which is actuated in response to actuation of saidswitch assembly.
 8. The hand-held light assembly of claim 7, whereinsaid solenoid includes a shuttle member connected to said proximal endof said light guide, said shuttle member being moveable to responsivelycause said proximal end of said light guide to be moved towards and awayfrom said light source to thereby effect said at least two lightintensities.
 9. The hand-held light assembly of claim 7, wherein saidshutter assembly includes a flexible shutter band having one endconnected to a shuttle member moveable within said solenoid and anopposite end moveable into and out of covering relationship with saidproximal end of said light guide in response to movement of said shuttlemember to there effect said at least two light intensities.
 10. Thehand-held light assembly of claim 7, wherein said shutter assemblyincludes a shutter paddle connected operatively to said solenoid formovement into and out of covering relationship with said proximal end ofsaid light guide to effect said at least two light intensities.
 11. Thehand-held light assembly of claim 10, wherein said shutter paddle ismoved radially into and out of said covering relationship with respectto said proximal end of said light guide.
 12. The hand-held lightassembly of claim 10, wherein said shutter paddle is moved rotationallyinto and out of said covering relationship with respect to said proximalend of said light guide.
 13. The hand-held light assembly of claim 12,wherein said shutter assembly includes a drive shaft disposed generallyparallel to said proximal end of said light guide, said drive shafthaving one end connected to said solenoid, and an opposite end connectedto said shutter paddle such that activation of said solenoid rotatessaid drive shaft which, in turn, rotates said shutter paddle into andout of said covering relationship.
 14. The hand-held light assembly ofclaim 1, wherein said light source is positioned remotely from saidhandpiece.
 15. The hand-held light assembly of claim 14, herein saidassembly includes a optical fiber element which optically connects saidlight source and said light guide of said handpiece.
 16. The hand-heldlight assembly of claim 1, 2, 14 or 15, wherein said at least twodifferent light intensities discharged by said light guide onto thefield of view includes on and off light illumination conditions.
 17. Ahand-held surgical light comprising: a handpiece adapted to be graspedand manipulated by a surgeon; a light source for generating a source ofvisible light; a light guide having a distal end projecting forwardly ofsaid handpiece and having a proximal end in optical communication withsaid light source; and a membrane switch carried by said handpiece andelectrically connected to said light source so as to change intensitiesof visible light generated by said light source, wherein said membraneswitch includes (i) a central electrically conductive cylindrical basemember, and a tubular electrically conductive elastomeric outer memberconcentrically sleeved over said base member so as to establish anannular space therebetween, wherein contact between said outer memberand said base member causes said change of visible light intensities.18. The hand-held light assembly of claim 17, wherein said light sourceis contained within said handpiece.
 19. The hand-held light assembly ofclaim 18, wherein said handpiece includes a source of electrical powerelectrically connected to said switch and said light source.
 20. Thehand-held light assembly of claim 17, wherein said light source isremotely positioned relative to said handpiece, and wherein said lightsource includes an electrically-operable shutter assembly connectedoperatively to said membrane switch to effect said change of visiblelight intensities.
 21. The hand-held light assembly of claim 20, whereinsaid base member is tubular and is sleeved over said hand-piece.
 22. Thehand-held light assembly of claim 21, wherein said membrane switchincludes proximal and distal electrically non-conductive mounting ringswhich are fixed to and concentrically separate said tubular electricallyconductive elastomeric member and said electrically conductive basemember.
 23. The hand-held light assembly of claim 20, 21 or 22, whereinsaid shutter assembly includes a solenoid which is actuated in responseto actuation of said membrane switch.
 24. The hand-held light assemblyof claim 23, wherein said solenoid includes a shuttle member connectedto said proximal end of said light guide, said shuttle member beingmoveable to responsively cause said proximal end of said light guide tobe moved towards and away from said light source to thereby effect saidat least two light intensities.
 25. The hand-held light assembly ofclaim 23, wherein said shutter assembly includes a flexible shutter bandhaving one end connected to a shuttle member moveable within saidsolenoid and an opposite end moveable into and out of coveringrelationship with said proximal end of said light guide in response tomovement of said shuttle member to there effect said change of visiblelight intensities.
 26. The hand-held light assembly of claim 23, whereinsaid shutter assembly includes a shutter paddle connected operatively tosaid solenoid for movement into and out of covering relationship withsaid proximal end of said light guide to effect said change of visiblelight intensities.
 27. The hand-held light assembly of claim 26, whereinsaid shutter paddle is moved radially into and out of said coveringrelationship with respect to said proximal end of said light guide. 28.The hand-held light assembly of claim 26, wherein said shutter paddle ismoved rotationally into and out of said covering relationship withrespect to said proximal end of said light guide.
 29. The hand-heldlight assembly of claim 28, wherein said shutter assembly includes adrive shaft disposed generally parallel to said proximal end of saidlight guide, said drive shaft having one end connected to said solenoid,and an opposite end connected to said shutter paddle such thatactivation of said solenoid rotates said drive shaft which, in turn,rotates said shutter paddle into and out of said covering relationship.30. The hand-held light assembly of claim 17, wherein said base memberis tubular and is sleeved over said hand-piece.
 31. A hand-held surgicallight comprising: a handpiece; a fiber optic light guide projectingforwardly of said hand piece; a source of visible light opticallyconnected to said light guide so that visible light generated by saidsource thereof may be projected from a distal end of said light guideonto a surgical field of view; and a switch carried by said handpieceand operatively connected to said source of visible light to allowselection of visible light intensities projected from said distal end ofsaid light guide, wherein said switch includes an inner electricallyconductive cylindrical base coaxial with said handpiece, and an outerelectrically conductive elastomeric band circumferentially andconcentrically surrounding said inner base in spaced relation thereto.32. The hand-held surgical light of claim 31, wherein said source ofvisible light includes a shutter assembly operatively connected to saidswitch which changes intensities of visible light projected from saiddistal end of said light guide in response to switch activation.
 33. Thehand-held surgical light of claims 31, wherein said inner base is acylindrical member concentrically sleeved over an exterior surface ofsaid handpiece.
 34. The hand-held surgical light of claim 33, whereinsaid switch includes proximal and distal mounting rings longitudinallyseparated from one another, to maintain said spaced relation of saidinner base and outer elastomeric band.